DALLAS - United Airlines is trying again to raise prices after a similar move failed earlier this month.

United said Wednesday that it raised prices for travel within the U.S. by up to $20 per round trip.

United Continental Holdings Inc. said it raised prices $2 each way for flights under 500 miles, $3 for 501 to 1,000 miles, $5 for 1,001 to 2,000 miles, and $10 each way for flights longer than 2,000 miles or involving Hawaii or Alaska.United tried to raise prices by up to $10 per round trip on Jan. 3 but rolled back the increase after others, notably Southwest Airlines Co., kept their fares unchanged.

JPMorgan analyst Jamie Baker, who spotted Wednesday's increase shortly after United entered it in ticket-distribution systems, said he expected some other big airlines to raise prices too but that Southwest's support would be needed for the increase to stick.

Southwest carries more passengers within the U.S. than any airline and wields great influence over prices on many routes.

According to Baker, the airlines imposed five broad fare increases last year and 11 in 2011.